Walker should start. He shouldn't be a bench player with his talent and the team's need for offensive creation. Assuming everyone stays, it might be best for White to come off the bench to preserve his body. He does seem to get stress injuries quite a bit. Have Murray, Walker, McDermott (or Vassell if he has it together), Johnson and Poeltl start. Bring in Derrick as the first sub for the SF and slide Lonnie over. Bring Forbes (since he's going to be there) in for Murray, Young in for Walker and Eubanks/Landale in for Poeltl on the next sub. Then top it off by bringing in Vassell/McDermott for Johnson. That should prevent the spacing from ever being bad. The worst it gets is with the starting lineup, but you aren't going to bench Murray, Johnson or Poeltl if they're on the team. Hopefully the former two are able to shoot better next season.
Murray, White
Walker, Forbes
McDermott, Vassell
Johnson, Young
Poeltl, Eubanks/Landale
Hopefully Devin's three-and-D chops are ready to go so he can start. Otherwise defense in that first unit is going to be interesting.